Thanks for reply.
You can test it at your own end as well. Just add "locked: true" to any of the COLUMN of the GRID. Then you can see LOCK and UNLOCK option in the column property (Just below the column hide/show).
After that you can see Lock/Unlock state in not maintained.

Issue with Ext.state.CookieProvider

It is also having issue with Ext.state.CookieProvider. Locking and Unlocking State is not persists even by using Ext.state.CookieProvider. I think it is the ExtJs issue.
If anybody has any workaround for this, then please let me know. Thanks